Machine for welding



June 7, 1932. J. w. MEADOWCROFT 1,

MACHINE FOR WELDING Original Filed March 18. 1927 3 Sheets-Sheet 1 INVENTOR.

Joseph W. Meadowcroft A TTOR NE Y.

June 7, 1932- J. w. MEADowcRoFT MACHINE FOR WELDING Original Filed March18. 1927 5 Sheets-Sheet 2 Ill! 1 INVENTOR. Joseph W. Meadowcrof t BY Z IATER/wa June 7, 1932. J. w. MEADOWCROFT MACHINE FOR WELDING OriginalFiled March 18, 1927 3 Sheets-Sheet J05 cphw, Meadowcrof i.

A 'ITOR NE Y.

Patented June 7, 193a UNETED STATS rarar OFFICE JOSEPH W. MEADOWCROFT,OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR T EDWARD G. BUDD MANUFACTURING-COMPANY, OF PHILADELPHIA, PENNSYLVANIA, .A. COR- PORATION OFPENNSYLVANIA MACHINE FOR WELDING Original application filed Karen. 18,19%, Serial No. 176,317. Divided and this application filed April 22,1929. Serial ltfo. 357,023.

' where it will be desirable to use the invention,

besides the one just mentioned as an example.

This application is a division of my prlor application Serial No.176,317, filed March 18, 1927 for method of and machine for welding, inwhich the method of my invention is claimed.

Ordinarily when two adjacent sheets of three or more overlapped sheetsof metal are welded together by spot welding a weld mark is made uponthe outer surface of the third or other sheet. That this is the case isreadily seen, as when such welding is done, it is either necessarytohave one of the electrodes engage the outer surface of this exteriorsheet or to provide openings through the same for the passage of theelectrode to the interior sheet. The welds in the first instance arefound to be unsatisfactory because of the high resistance caused by thethickness of the three or more sheets of metal, and it is evident, thatoften the exterior sheets could not be provided with the openingssuggested in the latter. Especially, is this found to be the case, wherethe outer panel of an automobile door is flanged around a flange of thedoor rail and such flanged portion of the panel is welded to the railflange to fprm a door overlap. Accordingly, the practice is to use arcwelding in place of the resistance welding; This practice isunsatisfactory both from the standpoint of the quality of the welds andthat of quantity production. The door rails are of heavier gauge thanthe panels and consequently the panels respond more quickly to the heatof the arc, with the result that the deposit from the welding wire iswelded to the panel instead-of the panel and rail. It is clear that suchwelds do not stand up in use. An additional step inalso necessary wherearc welding is used, namely, the

weld humps must be ground down and pol- The principal object of theinvention is to provide a method of and a machine for spot weldingtogether two adjacent sheets of three or more overlapped sheets of metalwithout leaving a weld mark upon the other sheets, or requiring theforming of openings in such sheets for the passage of an electrode.

Other objects and advantages will become apparent from time to time asthe description proceeds.

The invention contemplates accomplishing its principal objective byconnecting one of the two adjacent sheets of three or more overlappedsheets of metal with one side of a welding circuit independently of theother sheets, and then closing the welding circuit by a direct localizedpressure contact between the other side of said circuit and the other ofsaid adjacent sheets.

In carrying out the invention, a welding machine is used wherein one ofthe electrodes is in the form of a clamp adapted to be connectedelectrically, either directly or indirectly, with one of the adjacentsheets to be welded together, anotherelectrodeis rectilinearly movableso as tohave pressure contact with the other of said adjacent sheets,

and means is provided for resisting the thrust of such pressure contactof the electrode. There are, in addition, certain details ofconstruction 1n the machine which are novel and which will be describedat length during the course of the description.

A specific description of the illustrated embodiments of the inventionnow follows, and should be read in connection with the accompanyingdrawings wherein,

Flg. 1 is a side elevation of a welding machine constructed inaccordance with the invention,

Fig. 2 isv a front elevation of the machine,

Fig. 3 is a sectional view showing one of the electrodes clampeddirectly to the door rail of an automobile door and another electrodeengaging the inturned flange of the outer panel of the door with apressure contact to weld the same to the overlap flange of the doorrail,

Fig. 4 is another View showing the door rail indirectly connected to theelectrode through tIhe intermediary of the lock panel of the c oor.

The welding machine, illustrated in Figs. 1 and 2, is in manyparticulars of the conventional type. The machine comprises a base stand1, with supporting uprights 2, and a horizontally supporting member orarm 3 arranged at the top of the machine, as is usual in most spotwelding machine frames. These frame members are secured together andinterbraced by means of gusset plates 4. The machine is provided withthe customary switch 5 and transformer 6. However, it should be notedthat the transformer is mounted in an unusual position upon the top ofthe frame, so that the leads of the secondary circuit may be carried asdirectly as possible to the electrodes of the machine. The leads 7 and 8of the primary circuit extend in the usual manner from the switch to thetransformer. The description thus far has not gone into details ofconstruction, since the machine frame may be of any well known type, andone skilled in the art will readily understand such to be the case.

The outer end of the upper arm 3 is provided with the usual cylinder 9through which the plunger 10, carrying the rectilinearly movableelectrode is adapted to slide. The movement of the plunger is controlledby an actuating lever 11, swingably mounted in trunnions 12 andcounterbalanced by the customary counterweight 13.

A push button switch 14 for controlling the primary circuit is shownconnected to the handle of the lever 11, but it should be understoodthat the usual Thompson switch could be employed if desired.

The movable electrode is connected to the secondary of the transformerby the connection 15, and comprises the usual construction, being formedby the conducting bars 16 and 17. The electrode proper or die point 18is secured in the outer end of the bar 17. The electrode 18 is connectedby conduits 19 and 20 to a source of water supply whereby the same iscooled.

The other electrode, shown in Figures 1, 2 and 3, comprises a flat bar21, of hard drawn copper or other material, which is, in turn, connectedto a plate 22 having a detachable connection'to a water jacket andterminal connection 23.

The plate 22 has a three point contact with the plate 21 through thefastening means 21 and the head of the attaching member 22".

This member 22 extends through an opening in the plate 22 and isthreaded into a tapped opening in the connection 23. A. set screw orother means may be employed to lock the member in position. The waterjacket and terminal connection 23 is provided with a central portion forreceiving the lead of the welding circuit, while the surrounding portionconstitutes a water jacket. This electrode 21 is connected by a flexiblelead 24 to the secondary of the transformer 6. Connected to the lead 24by clamp 25 is a cable 26 which is countcrweighted, so as to normallyhold the electrode in elevated position. The water jacket 23 is adaptedto receive a circulation of water through conduits 27 and 28 connectedthereto by nipples 27 and 28 Clamp blocks or bases 29 and 30 arearranged upon the upper surface of the electrode 21 and pivotallysupport link clamps 31 and 32. Although only two clamps are shown, itshould be understood that any number might be used and the form thereofmay be of any suitable design, the clamps shown not having beendescribed in detail for this reason. The electrode 21 is readily movedaround, thus facilitating its application to the work, because of itsflexible suspension.

The present machine will here be seen to vary considerably from theusual type, in that, the lower arm ordinarily carrying the fixedelectrode is omitted.

An undersupport is provided for supporting the work so that the movableelectrode can exert pressure thereon. This support comprises a baseblock 33, screwed or otherwise arranged upon the fioor, and a verticallyextending substantially tubular hollow member 34. At the upper end ofthe member 34 is an enlarged collar, through an opening in which a setscrew 35 is adapted to operate. A rod member 36 is arranged within thetubular upright 34 and is adapted to have sliding movement therein, sothat it may be adjusted in various positions. The upper end of the rodis provided with a yoke 37 in which a supporting block 38 is pivotallymounted. This block is adapted to underlie the work in substantialalignment with the movable electrode, and since the same is pivotallymounted, it may adjust itself to slight irregularities in the surfacethereof. It has also been shown that the rod 36 is verticallyadjustable, and also that it may be turned within the tubular member 34,thus indicat ing that in effect the supporting block 38 has universalmovement with respect to the Work. In order that a large amount of heatmay be carried off from that portion of the work eugaged by thesupporting block, and thus maintain such portion below weldingtemperature. the block is preferably formed of a material having a highdegree of thermal conductivity, such as copper. The cooling of thisportion of the work is further effected by the provision of coolingmeans for the supporting block in the nature of a circulating stream ofwater supplied'to the same by the conduits 19 and 39.

In Fig. 3 of the drawings is shown the manner in which the machine maybe used to weld an inturned flange of an outer anel of an automobiledoor to the overlap ange of the door rail.

The electrode 21 is placed between the side rails 40 and 41 of the doorand the clamps 31 and 32 are then thrown to clamp the electrode and doorrails together. a

The under supporting member is then arranged beneath the overlap flangeof the door and the rectilinearly movable electrode is brought intopressure contact with the inturned flange 42 of the outer panel 43. Thewelding circuit is thus completed, passing through the electrode 18,flange 42, door rail '40, and electrode 21. Thus the flange 42 is weldedto the overlap flange of the rail without leaving a weld mark upon theouter surface of the outer panel.

In Fig. 4 a slightly modified form is shown, the clamp electrode in thisform being adapted to be connected indirectly to' the rail through thelock panel 44 of the door. The clamp electrode 21 shown in this form hasa curved end 45 adapted to grip one edge of the lock panel while theclamps grip the other edge. The welding operation in this form is thesame as in that previously described. The welding circuit beingdifl'erent, however, as it passes from electrode 18, through flange 42,rail 40, lock panel 44, and electrode 21. The lock panel is welded tothe rail and it will be evident that good electrical connection isefl'ected by the welds.

It has been found that the welds made by the methods described, are moreperfect throughout the door if the secondary voltage is increased from7.3 to 18. The increased voltage will get the current to the point ofthe weld without undue throwing. The ground connection will be spreadout so that the current may reach the regions of the welds by theshortest possible route consistent with the simple connection. Thisincrease in voltage is most important and has decided beneficialresults, as it not only per- .fects each weld but also greatly increasesthe speed of each welding operation thereby improving prodnction.

The modificatidns and adaptations of which the invention is susceptibleare only limited by the scope of the appended claims.

What I claim is:

1. A spot welding machine adapted for welding together two adjacentsheets of three or more overlapped sheets of metal comprising anelectrode having clamping means for securing the electrode in electricalconnection with one of the sheets to be welded, a conventionalrectilinearly movable electrode adapted to be brought into pressureengagement selectively at different points with the other sheet to bewelded, and supporting means engaging the under side ofthe sheets inline with the path of movement of the last ing swiveled upon the freeend of a flexible lead connection whereby the electrode will havesubstantially universal movement with respect to the machine, aconventional rectilinearly movable electrode adapted to be brought intopressure engagement selectively at difi'erent points on the other sheetto be welded, and adjustable supporting means arranged in line with thepath of movement of the last-named electrode and supporting the sheetsagainst the pressure exerted thereby.

3. In a spot welding machine, an electrode comprising a plate likemember of substantial area, clamps arranged adjacent the edges of saidmember for clamping the same in electrical connection with the materialto be welded, a second plate secured upon said first-named plate andelectrically connected thereto. and a sleeve for receiving one end ofthe secondary lead connected to said lastnamed plate member by a swivelconnection.

4. A spot welding machine adapted for welding together two overlappedsheets of metal comprising an electrode having clampring means forsecuring the electrode in electrical connection with one of the sheetsto be welded, a conventional rectilinearly-movable electrode adapted tobe brought into pressure engagement selectively at different points withthe other sheet to be welded, and supporting means engaging the underside of the sheets in line with the path of movement of the last namedelectrode so as to resist the pressure exerted thereby.

5. A spot welding machine adapted for welding together two overlappedsheets of metal comprising an electrode having clamping means forsecuring it in electrical connection with one of the sheets to bewelded.

a conventional rectilinearly movable electrode adapted to be broughtinto pressure engagement successively at different points with one ofthe sheets to be welded. and supporting means arranged to engage thesheets in opposed relation to said rectilinearlymovable electrode toresist the pressure exerted thereby, said supporting means engaging thesheets over a relatively large area compared with the surface engaged bysaid movable electrode and having a relatively high heat conductivity.

6. A spot welding machine adapted for welding together two overlappedsheets of metal comprising an electrode attached to a flexible conductor'to permit free movement thereof and-provided with clamping means ofrelatively high thermal conductively engaging the sheets in opposedrelation to said last named electrode so as to resist pressure exertedthereby, and reduce the temperature of the metal surface engaging thesupport to prevent the formation of weld marks.

7. A spot welding machine adapted for welding together two overlappedsheets of metal comprising a flexibly connected electrode havingclamping means for securing the electrode in electrical connection withone of the sheets to be welded, a conventional rectilinearly-movableelectrode adapted to be brought into pressure engagement selectively atdifferent points with the one of the sheets to be welded, and supportingmeans mounted for universal movement for engaging the sheets in opposedrelation to said last-named electrode so as to resist pressure thereby.

8. A spot welding machine having a work support associated therewith,and a pair of movable electrodes, one of said electrodes engaging thework at a point opposite said support, and the other engaging the workat an unsupported portion thereof to complete the welding circuitthrough the work.

9. A spot welding machine having a work support associated therewith,and a pair of movable electrodes adapted when simultaneously in contactwith the work to close a welding circuit therethrough, said electrodesbeing movable with respect to each other and with respect to the machineas a whole, one of said electrodes engaging the work at a point oppositesaid support, and the other at a portion thereof remote from said pointto complete the welding circuit through the work.

10. A spot welding machine having a work support provided with awork-engaging surface, and mounted for movement to permit its workengaging surface to lie flat against the surface of the work in positionfor welding, and a pair of electrodes adapted when simultaneously incontact with the work'to close a welding circuit therethrough, oneelectrode engaging the work at a point opposite said work support andthe other at a point remote from said first-mentioned point.

11. A spot welding machine having a work support associated therewithadapted to lie I fiat against the surface of the work near the part tobe welded, a pair of movable electrodes, one of said electrodes beingadapted to engage the work at a point opposite said support, meansindependent ofthe support for closing a welding current through thework, said work support being formed of a work, said work support beingformed of copper.

13. A spot welding machine having a work support associated therewith,and a pair of movable electrodes, one of said electrodes engaging thework at a point opposite said support, and the other engaging the workat another portion remote from said support to complete the weldingcircuit through the wor and means for maintaining an electrical pressuredifference between the Work and the work engaging electrode in excess of15 volts prior to closing of the welding circuit. 4

14. A spot welding machine having a work support associated therewith,and a pair of movable electrodes, one of said electrodes engaging thework at a point opposite said support, and the other engaging the workat another portion remote from said support to complete the weldingcircuit through the work.

In testimony whereof I hereunto afiix my signature.

JOSEPH W. MEADOWCROFT.

